Fire alarm system



Dec. 17, 1963 Y A. c. CAPELLE 3,114,901

FIRE ALARM SYSTEM Filed March 26, 1958 4 Sheets-Sheet l Fig. I

Arfhur C. Capella INVENTOK.

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FIRE ALARM SYSTEM Filed March 26, 1958 4 Sheets-Sheet 2 Fig.9

Arfhur 6. Cape/la INVENTOR.

Attorneys Dec. 17, 1963 CAPELLE 3,114,901

FIRE ALARM SYSTEM Filed March 26. 1958 4 Sheets-Sheet 3 Arthur C. Cape/ls JNVENTOR.

M M21. BY an W EMWLW Dec. 17, 1963 A. c. CAPELLE 3,114,901

FIRE ALARM SYSTEM Filed March 26, 1958 4 Sheets-Sheet 4 Fig.

Fig/4 Arthur C. ane/le INVENTOR.

United States Patent 3,114,9h1l lFlRE ALARM SYSTEM Arthur C. Capelle, 9811 Royal Palm Drive, San Remo Shores, liradenton, Fla. Filed Mar. 26, 1953, gar. No. 724,1tlll 12 Claims. (Cl. Edit-227) This invention relates generally to alarm systems and more particularly to an alarm system particularly designed to detect fires and to actuate an audible signal indicating the fire.

The need for fire alarm protection cannot be neglected. Each year many millions of dollars worth of property are lost due to fire. Further, numerous lives are lost due to fire and panic often resulting therefrom. Needless to say, this property damage and loss of life could be substantially lessened if the proper precautions to prevent fires or at least to properly notify fire department authorities of fires at an early stage were taken. Many fire alarm systems have been developed over the years which have been designed and devised to indicate the existence of a proximate fire. Generally these fire alarm systems detect the presence of a fire by the heat given off by a fire which would, for instance, bend a heat sensitive bimetallic element to close a pair of contacts to an alarm. Most of these former systems have been expensive and cumbersome in that separate alarms v ere required in various parts of a building where fire detectors were located or lengthy complex wiring was required to connect the various fire detectors to a single alarm. The complexity of the systems, of course, cause them to be expensive and therefore the systems never truly became popular or abundant. An imperative need therefore existecl for the development of inexpensive, simple, and reliable fire alarm system. It is therefore the principal object of this invention to provide a novel and improved fire alarm system which is characterized particularly by its simplicity in installation and construction and its reliability for detection and alarm indication.

In order to minimize production and installation costs, it has been found that to utilize existing building circuitry materially lessens any expense that may be incurred through installation of this protective system. Therefore, it is a further object of this invention to provide a fire alarm system which utilizes detector elements particularly designed to be plugged into existing building circuitry to use the circuitry for conveying actuating impulses to alarm devices.

A still further object of this invention is to provide novel and improved plug-in fire detector elements which form an integral part of the fire alarm system.

It is a still further object of this invention to provide a novel and improved fire alarm system which is capable of detecting defective and shorted wiring between walls, ceiling and floors and which will sound an alarm before a fire actually starts.

it is more particularly an object of this invention to provide a fire alarm system which may discriminate between actual fires and normal short-circuits in the building circuitry.

It is a still further object of this invention to provide a novel fuse-alarm element which may be utilized as an integral part of the fire alarm system.

It is a still further object of this invention to provide a novel and improved plug-in fire alarm system which may be incorporated with any existing building electrical distribution system.

in accordance with the above stated objects, below is described in particularity, the principles of construction and operation of the elements comprising the novel fire alarm system. Of course, the principal design considera- Ice tions were to achieve the maximum fire protection at the minimum of installation and maintenance cost. To do this, -ne detector elements were developed which were temperature responsive and reacted to a fire so as to close a pair of electrical contacts. The fire detector and electrical contacts are intended to be inserted in a normal electrical outlet box. When the fire or heat causes the contacts of the fire detector to close, the electrical distribution line will be shorted and a line fuse in the panel box will blow. (For all disclosed embodiments except one, the systems are equally effective where line breaker switches are used instead of fuses.) This will bring a portion of the hot wire down to neutral through the closed contacts of the fire detector. Elements of an alarm device connected between the portion of the hot wire brought down to neutral and a second hot Wire will then be energized to actuate an audible alarm. Before the fuse blew, of course, the alarm device remained unenergized because it was connected at both its terminals to a pair of hot wires having no voltage drop therebetween. Though the system would detect all fires, a normal blown fuse caused by a short circuit would likewise actuate the audible alarm. Therefore, the further more complex and more expensive system is disclosed for discriminating between the fire and a conventional shortcircuit. This further system utilizes a step relay which is topped by increasing temperatures. Therefore, a conventional short-circuit which is generally of a single duration will not actuate an alarm device but fire with an ever increasing temperature will continue to step the relay until, after a predetermined number of steps, the audible alarm is actuated. A further feature of the invention allows for a semi-discriminating system which would have a cost falling somewhere between the cost of a nondiscriminating and a discriminating system. The semidiscriminating system includes a time delay device which provides a time interval between the moment the fuse blows and the audible alarm is actuated. This enables a person to remove the blown fuse and the short circuit cause (which is generally known) before the alarm is ctuated.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and clai icd, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a schematic diagram of a conventional building wiring system;

FIGURE 2 is a perspective view of one embodiment of fire detector element for use in a discriminating fire alarm system;

FKGURE 3 is a vertical sectional view taken substantially along the plane 3-3 of FlGURE 2;

FIGURE 4 is a horizontal sectional view taken substantially along the plane 'i i of FIGURE 3;

FIGURE 5 is a sectional view of a second embodiment of a fire detector utilized in discriminating fire alarm systems;

FIGURE 6 is a sectional view taken substantially along the plane d-6 of FIGURE 5 FIGURE 7 is a sectional view of a third embodiment of a fire detector for utilization in a discriminating type fire alarm system;

FlGURE 8 is a sectional view taken substantially along the plane 8-& of FIGURE 7;

FIGURE 9 is a circuit diagram of a semi-discriminating fire alarm system;

FIGURE 10 is a circuit diagram of a discriminating fire alarm system;

FIGURE ll is a sectional view through a fuse-alarm U device to be utilized in conjunction with the fire alarm system;

FIGURE 12 is a circuit diagram of the device of FIG- URE 11;

FIGURE 13 illustrates a fire detector in its most basic form;

FIGURE 14 illustrates the circuit of a basic semi-discriminating fire alarm system;

FIGURE 15 illustrates a polarized plug device to be utilized in conjunction with the circuit of FIGURE 14.

With continuing reference to the drawings, and initial reference to FTGURE 1, the circuit there presented represents one form of a conventional electric distribution system. Of course, many building electrical distribution systems are used and the teachings of this invention can be well adapted to any conventional system. in the system of FIGURE 1, L and L represent a pair of lines carrying current from a utility distribution transformer to the building distribution system. The line N represents the neutral line which is generally connected to the building ground which, for instance, may be electrically connected to a water pipe. Conventionally, approximately 1 10 volts will exist between the neutral and either line with approximately 220 volts existing between the lines. 16) and 12. represent main switches for providing electric power to the building circuitry. Fuses 14 and 16 represent main line fuses for protecting the wiring from an overload and preventing a fire which may be caused by a current overload. A plurality of leads as at 18, 2t) and 22; are tapped from the lines. As shown in FTGURE 1 each of the leads is equipped with a separate fuse as is shown at 24. A resistor, R is shown electrically connected between the line L and the neutral wire. This resistor R is intended to represent any 110 volt load as, for instance, a light. Of course, any 110 volt load would be fed in the same manner as R between one of the lines, either L or L to the neutral wire. Terminals Bill and 32 on FIGURE 1 represent two contacts of wall outlet which may, for instance, receive any of the fire detectors to be more specifically described below.

With initial reference to FIGURE 13, numerals and 36 represent a pair of male conductor members adapted to be electrically received in female contacts and The conductor 34 is electrically connected to a bimetalli strip 38 carrying a contact 45 on the end thereof. A contact 4-2 is placed proximate the contact 4 and is adapted to be contacted thereby upon a temperature increase in the vicinity of the fire detector generally represented by 44. It will be apparent that contacts and 42 are normally opened and only in the event of a fire or an extreme rise in temperature will they contact. Upon a direct connection of the contacts 46 and 42, the points 39 and 32 will be short circuited and the fuse 241 would normally blow. By utilizing the device shown .in FlGURES ll and 12 in place of the fuse 24, the short oircuiting of points 36 and 32 due to a fire proximate the bimetallic strip 38 will cause the device of FlGURE 11 to become energized so as to create an audible alarm.

The device of FIGURE 11 includes a conductive cap portion 48 which may be threadedly engaged upon a neck portion 59 as at 52. Held within a. hollow '4 created through the neck portion Sli is a fuse 56 including conventional conductive end portions 58 and bridged by a fusible member 62 surrounded by a transparent cylinder 64. An insulative collar portion 66 surrounds the neck A metallic threaded portion 68 is affixed to the collar as at 71 and extends rearwardly to a second insulative portion '72 to which it is also affixed. The second insulative portion 72 surrounds an electricallyconductive magnctic core portion '74 upon which is wound a bell core '76. An insulated spacer '7 8 electrically separates the neck portion 519 from the core '74. The fuse 56 sets in a hol low in the core 7 4 and electrically connects the cap vith the core '74. A bell structure is carried by flanges 82 on the rear of the insulative member 72. The bell a is carried on a resilient elongated strip 85 which is supported as at 12 illustrates the schematic wiring of the device of FTGURE 11 wherein '74 again represents the core and 76 the conductive coil. 68 epresents the threads which would conventionally form one tenntinal of the circuit when utilized in a conventional fuse outlet. The cap 48 would generally form the second terminal with the fuse 56 connecting them and shunting the coil "76. The electrical connection through this device may be easi y followed. That is, f'om cap 48, an electrical path is defined through collar St? to wire 91 to coil '76 through wire 92 to core '74 to the threaded portion 63. A parallel path may be followed through the fuse from cap to end portion 55, fusible strip 62, end portion as, to core 74 and threaded portion 68.

When the device of FIGURE 11 is utilized in the place of fuse 24, under normal circumstances a circuit will function in a conventional manner. However, when the contacts and 42 of fire detector 3% close the points 30 and 32 are shorted and fusible strip as will open, thereby opening the circuit through fuse 56. This action will place a voltage across the coil '76 and cause the bell structure 8% to become actuated and give o'lf an audible signal. More particularly, the voltage will be applied across the coil 76 because the point 3i will be connected to the neutral wire through the contacts 451 and 42. of the fire detector This fire detector system clearly then indicates the presence of a fire without any external wiring between the fire detector and the audible alarm. However, any normal short in the lines caused by a reason other than fire would likewise actuate the alarm structure 8d, thereby resulting in a false alarm. It should of course be apparent that instead of utilization of the device of FEGURE 11 for fuse 24, it may replace fuse 14 just as easily if the proper fuse values are taken into account.

An alternative to the fuse-alarm shown in FIGURE 11 would be the utilization of the devices illustrated in FTG- URES 14 and 15. More particularly, with the fire detector still connected across the points 31 and 32, a female polarized outlet 94 may be utilized instead of either the fuse 14 or The outlet 94- may be accommodated in the same way as the conventional fuse having a threaded portion 96 and an end contact portion 98. The portions 96 and 9? electrically communicate with a pair of female receptacles 113i, and 192 which are polarized as may be seen in FiGURE 15. The receptacles 1th} and i i-2. may electrically accommodate a pair of male prongs and 1th; which electrically extends through leads 16d and 11% to a parallel combination of a fuse 112 and a transformer primary coil 114. The coil 114 is wound on a core 115 which also carries a secondary coil 113. In series with the secondary coil 118 is a heating coil 12% which is adapted to control bimetallic arm 122 carrying a movable contact 12 adapted to electrically contact a fixed contact 125. The fixed contact 126 electrically extends to a conventional bell 123.

In the utilization of the devices of FIGURES l4 and 15 when the contacts 411 and 42 of the fire detector 44 closes, an overload current will be drawn and the fuse 112 in series with the contacts 411 and 42 will blow. When fuse 112 opens, a voltage will be applied across the primary coil 114 which would be induced in the secondary coil 118. A current through coil 12. 5 will tend to heat the bimetallic strip 122 which will after a predetermined time carry the contact 12 into electrical connection with contact 126. The bell 128 will then, of course, be actuated. It is noted that the heating coil 126 provides a time-delay between the time of the opening of fuse 112 until the time of the bell ringing of bell 128. This timedelay is provided as an advantage over the device of FIGURE 11. That is, the device of FIGURE 11 is nondiscriminating in that a fire or a conventional short circuit will actuate the alarm in the same manner. The device of FIGUR 14 will not, however, immediately actuate the alarn. Generally, when an individual plugs in an appliance and the fuse blows, he is aware of the cause of the short circuit or the overload. He may then proceed to the fuse box to replace the blown fuse, as at 112, and the bell 128 vill not be ringing in this interim. However, if the fuse blowing is caused by a fire, he will not be aware of it and after a predetermined time a bell 123 will notify him of the fire. We will therefore speak of the device in FIGURE 14 as a semi-discriminating circuit. That is, though the circuit itself cannot discriminate between a fire and a short, a person is allowed sulficient time in order to remove the shorting cause.

Next referring to the circuit of FIGURE 9, there is shown a semi-discriminating fire alarm system which may be utilized with the distribution system of FIGURE 1 and is adapted to accommodate a plurality of fire detcctors. More particularly, numeral tilt, represents a terminal adapted to be connected to the neutral wire shown in FlGURE 1 and numeral 132 the terminal to be connected to either one of the lines shown as L or L The neutral terminal 13d extends to a plurality of normally open knife blade switches as 13 i which are controlled by a series of relay coils 136. The principles of this circuit can best be explained by reference simply to the elements enclosed in the dotted line rectangle with the understanding that the relays shown outside of the dotted line rectangle refer to devices electrically connected in parallel with the relay 13d and knife blade 134 and operate in an identical manner. The relay coil ass is wound on a magnetic core 138 and terminates in a pair of terminals Hi) and 142 which are intended to be connected in the distribution circuit on FTGURE 1 as at points 141 nd M3. It should be apparent that under normal operation no voltage will be impressed across the terminals l t-ll and in that the points Mill and 143 are connected to the same voltage line L The terminal 132 which is connected to a hot line, L or L extends through a switch fold and a fuse Md to a terminal M8 on relay coil 159, to a terminal 7.52 on a transformer primary winding 154, to a terminal 156 on. one side of an indicating lamp 158, to a terminal res on one side of a heating coil 162. The other side of all these elements extend to neutral terminal Tilt) through normally open switches as knife blade 13d and knife blade 135.

From the foregoing it should be apparent that when knife blades 134 and T35 close, the alarm system will be energized. The course of events may be as follows: (1) A short circuit will occur across points 3t and 32 due to the action of fire detector 44. (2) Fuse 24 will blow. (3) The potential of point l t-ll will therefore drop to the neutral line potential at point 332 and a voltage will therefore exist between points 141 and 143 and therefore the relay coil 136 which was formerly simply floating in the circuit will be energized through terminals 14d and connected respectively to the terminals Mil and (4) Knife blade 134- Will close and line 137 will be established as a neutral line directly connected to terminal (5) indicating lamp 158 will light. (6) Relay coil b will become energized. will close and thereby maintain the relay coil 1156) in its energized state (that is relay coil lldtl acts as a holding relay). (8) The heating coil 1162 will begin to heat. (9) The bimetallic strip 164 Will close and contact teriinal res. (10) The primary transformer 154': will become energized and the core 168 will induce a signal in the secondary coil 17d thereby actuating bell 1.72.

From the foregoing, it is apparent that FIGURE 9 with the time-delay heating coil 162 included therein shows a semi-discriminating fire alarm system. That is, the short across points 36 and 32 need not be caused by a fire but any conventional shorting of these points will have the same effect on the circuit of FIGURE 9. However, it is assumed that a person will be aware of a short caused by an appliance and the time-delay coil 162. will give the individual ample time to replace the blown fuse at 24-. However, if it be desired to utilize the system of FlGURE 9 as a non-discriminating system, it is only (7) Knife blade 1135' necessary to remove the heating coil 162 or to utilize the bell in a manner shown by the dotted line bell 173. The indicating light 158 visually indicates the short circuit across points 3t) and 32. Terminals 174 and 176 are auxiliary terminals which may be utilized to acuate other bells or alarm devices. Likewise, terminals 178 and 180 may operate further alarm devices on a non-discriminating basis. The holding relay coil lfitl, by maintaining a plate connected to the neutral wire, continues to actuate the alarm though the voltage across the terminals and 142 be removed. As noted above, any of the plurality of relays shown to the left of the dotted line marks may likewise actuate the system in the same manner as the relay coil 13o.

Further, in order to provide fire protection in the fuse panel area, the invention contemplates the installation of an outlet between the terminal 13d and lead 137. With a fire detector as illustrated in FIGURE 13, for instance, operatively carried by outlet fill, a fire will cause contacts and 4-2 to contact to actuate relay coil to energize the alarm circuitry.

The circuit of FTGURE 10 discloses a discriminating fire alarm system which may also be utilized as a nondis riminating or semi-discriminating system. Before gointo the details of the circuitry of FIGURE 10, it uld appear advantageous to discuss the discriminating fire detectors to be used in conjunction therewith.

The fire detector of FIGURE 2 includes rectangular perforated housing 1% perforated as at 192 and having electrically conductive male prongs i942 and 1% adapted to be electrically received within female receptacles as at 36' and 32 of FIGURE 1. The perforations 192 allow the ambient air to pass therethrough and effect a thermal spring 19?"; which is supported to the housing as at 200. A heating effect of the ambient air passing through the perforations 192 causes the thermal spring 198 to rotate a shaft 2132. journaled in the housing 199. The shaft 202 terminally carries a container 2%. The container 204 is substantially cylindrical with a series of ridges contained internally as at 2% and 268. The ridges 2% and 2th; separate the container 2% into a plurality of pool areas as Edit, 212; and 214. Each of the pool areas carries a pair of electrical contacts as 216 and 218. The terminals 2M and 218 are adapted to be electrically bridged by a pool of conductive fluid, as mercury, designated as The operation of this device is as follows:

Upon an increase in the temperature of the ambient air, the thermal spring res will rotate the shaft 292 in a manner such that the mercury pool 220 bridges the gap between 216 and 2%. Upon a further increase in ambient temperature the container 2M will tip further as it is carried by shaft 2% so that the mercury pool 220 then bridges terminal 2016 and 2.17. However, the terminals 216 and 217 are electrically connected together and the bridging effect is therefore of no consequence. However, as the container 20% continues to be carried by shaft 2% and due to the rise in the ambient temperature, the mercury pool 22f will bridge contact 217 and 219. Upon a further increase in temperature the bridging will again be broken and then restored. The ambient temperature therefore has the effect of intermittently shorting the male prongs 194 and 196 which are electrically connected as in parallel with terminals 217 and 219 as the ambient temperature increases. With the male prongs 194 and 1% electrically connected in the distribution circuit of FIGURE 1 across points 30 and 332, the fuse 24 will blow. As the electrical bridging effect of the mercury pool 2% is intermittently broken, the point fill intermittently assumes the neutral wire potential. The effect of this intermittent bridging and breaking on the accompanying circuitry will be discussed more fully in connection with the circuit below.

FTGURE 6 illustrates an alternative embodiment to the device illustrated in FTGURES 2 through 4. The embodiment of FIGURE 6 likewise has housing 230 which would also be perforated as at 232 for passing the ambient air to a thermal spring 2234 supported relatively to the housing at 236 and adapted to rotate a shaft 238 journaled in the housing 233. The shaft 233 carries three closed cylindrical containers as 2 3%"), 242 and 2 3 3 which are fixed to the shaft 23% at varying angles as clearly shown in FIGURE 5. Each of the containers 240, 242 and 244- carries a pool of conductive fluid as mercury 246 in the bottom thereof and a pair of terminals as at 248 and 25%. The terminals 248 and 256 are of course electrically connected to the male prongs 252 and 254 for electrical connection in the circuit of FIGURE 1 at 39 and 3-2. It should be further apparent that the pairs of terminals on the respective containers are connected in parallel with the male prongs 252. and 254-.

In operation, the embodiment of FlGURES 5 and 6 passes the ambient air and the temperature effects the thermal spring 234 so as to rotate the shaft 238 carrying the containers 240, 242 and 24 i therewith in a manner such that the conductive fiuid in each container bridges a pair of terminals as 2 28 and 259 for electrically shorting the male prongs 252 and 25 The angularity of the respective containers is so adjusted that an increase in ambient temperature causes an intermittent shorting and opening of the respective male prongs 252 and 254. For a purpose to be described more specifically below in conjunction with the explanation of the circuit of FIGURE 10.

FIGURES 7 and 8 illustrate a still further embodiment of the fire detector of the discriminating type again having a perforated housing 2-6-33 perforated as at 262 and carrying a pair of male prongs connected to a pair of elongated electrodes 264- and 266. The elongated electrodes 2&4 and 266 are carried on the inner perimeter of a cylindrical container 270 in a parallel relationship. The container 279 is supported on a shaft which may be rotated by thermal spring 272 supported by the housing at 2 74 and responsive to the ambient temperature. The

elongated electrode 266 is intermittently insulated as at 276 and 278 etc. and the container 27G again contains a pool of conductive fluid as mercury at 286.

In operation, as the ambient temperature increases as caused by fire, the thermal spring 2'72, will tend to tip the container 27 0 in such a manner so that the conductive fluid 280 electrically bridges the elongated electrode 264 and 266 shorting the male prongs across the points 3h and 32 of FIGURE 1. A further rise in temperature and a further tipping of the container 276? will break the bridging relationship of the mercury pool in that the insulation 278, for instance, will break the electrical contact between elongated electrodes 26 i and 266. It should further be apparent that as the ambient temperature increases, the container 27d will tip further and again the male prongs will be subjected to an intermediate shorting and opening at its terminals.

Now particularly referring to the circuitry of FIGURE 10, terminal 282 is adapted and intended to be connected to either one of lines L or L while terminal 264 is intended to be connected to the neutral wire of FIG- URE 1. Therefore, terminal 2M, is a not terminal which proceeds through a switch 286 and a fuse 263 to one side of a primary coil 388 at 290 to one side of a heating coil 3% at 292, to one side of a relay coil 35% at 234, to one side of an indicating lamp at 2%, to one side of a second indicating lamp 4% at 2%, to one side of a second coil 322 at 300, and to one side of a third coil 31% by line 302. All these elements could be actuated upon the connection of the neutral wire to the other side of the elements. The neutral wire 284 may be directly' traced to a terminal 3M- proximate to bridging bar 306 adapted to be actuated by a relay coil Shh on magnetic core 310. The terminals of the relay coil 3% are designated as 312 and 314 and are adapted to be electrically connected across the terminals 141 and lid?) of the circuit of FIGURE 1. Considering the three embodiments of the fire detectors as denoted above, upon an initial short-circuiting of points 39 and 32, terminal 141 will assume the potential of the neutral line and potential will therefore be impressed across terminals M1 and 143 connected to terminals 312 and 31d, thereby actuating relay coil and moving bridging bar into contact with point Edd. The bridging bar 336 further applies the neutral potential of terminal to terminal 3%. The neutral potential there proceeds to terminal 316 and through switch 318 to one side 329 of a relay coil 322 on magnetic core 324. The relay coil core combination 322. and 324 are adapted to actuate a pivotally mounted armature 326 which moves the ratchet or step gear 328 clockwise. The gear 328 carries an arm 33h therealong. The arm 3% is electrically connected to the neutral line as at 332 and is adapted to electrically contact any of the terminals 334-, 336, 338 and 344). This diagram arbitrarily shows a maximum of three steps for the relay but theoretically there would be no limit. The arm 33% is biased conuterclochwise by a spring 342. Assuming that the circuit of FIGURE 10 is initially as shown, and that when one of the fire detectors intermittently shorts the points 363 and 352 on the diagram of FIGURE 1, the relay coil 3% will cause bridging bar 3% to connect terminals 3%54': and 3'05 and the neutral potential will thereby be applied on one side of the relay coil 322 at 326. The armature at 228 will tend to rotate the ratchet gear 323 in a clockwise direction carrying the arm 33% into contact with the terminal 335. The arm 33% will apply a neutral potential to the contact 336 and a heating coil 344 which may be optionally utilized will start to heat if the contacts of switch 346 are closed. With the heating coil included in the circuit, the circuit is semidiscriminating that is, if the cause of the short circuit and the blown fuse Ed is removed, the circuit may be reset by the depression of a push switch at 346 which will bridge terminal 348 and 35d and apply a neutral potential to holding relay 352 pulling arm 354i toward the core 356 allowing the spring 342 to carry the terminal 334. If, however, the cause of the short is not removed the heating coil 344- will ultimately cause bimetallic strip 366 to contact fixed terminal 362 to apply a neutral potential at point are and actuate relay coil 366 on core 368. An actuation of relay coil 366 will cause the ganged bridging bars 37%, 3'72 and- 374 to contact respective terminals 3'76 and 3'78, 380 and 3 82 and 3'84 and 335. As these bridging bars fall, it will be apparent that a neutral voltage will be applied to the transformer primary 388 having transformer cores 3% and secondary 392. Apparently, this will actuate the audible alarm in the form of a bell 39d.

Retrogressing, if the heating coil 344- were not h1- cluded in the circuit, the circuit of FIGURE 10 would not be semi-discriminating but would be discriminating in that a conventional short circuit would move the arm 33b to the first position 336 where it would rest and no alarm would sound. However, if a fire actually did exist and the fire detectors intermittently energized the relay coil three times, the arm 330- would be moved to terminal 34d so that the neutral potential would be applied to point 354- and relay coil 366 would then be actuated to drop the bridging bars 37d, 372 and 374 to actuate the alarm devices. Even with the heating element 344 in the circuit shown in FlGURE 10, a fire will be detected by the operation of a circuit actuated through contact point 34th as follows: Upon the shortcircuiting of lines 30 and 32 due to a fire being detected by a thermal switch as shown in FIGURE 2, the fuse 24- will be caused to blow thus maintaining points 14-1 and 143 which are connected to points 312. and 314 of FIG- URE 10 at a different potential. This will cause relay 3% to be actuated causing bar 306 to bridge contacts Sit-i and 3%. This will connect the neutral line to one side of relay 324' causing it to be actuated and rotating the ratchet gear 32$ to point contact 336. This occurs when the mercury in the switch shown in FlGURE 2 bridges the first pair of contacts therein. Upon subsequent thermal energy being passed through the switch the tube holding the mercury will be further rotated and the circuit will be broken. However, upon further rotation of this tube due to the increased thermal activity due to a fire a second set of contacts will be bridged again actuating relay Fill? connecting the neutral line to relay 32.4 and causing the ratchet gear and contact arm 33%) to move to a point contact 338. Of course, the ratchet gear is held in its adjusted position by means of a pawl 35d electrically associated with the relay 356. Upon continuing thermal activity, the circuit is again broken but contact arm 330 will remain at point contact Then, before the bimetallic element 36% has suificient time to close contact 362, the mercury pool will further be rotated to a position where a third pair of contact elements is bridged again actuating relay which in turn allows actuation of ratchet gear 328 and contact arm 3% to move the same so that contact arm 33% is in contact with point contact It should be apparent that the heating element 344i causes closure of switch 36% to contact 362. The switch Saudis slow acting and will not close until after the mercury switch shown in FIGURE 2 has rotated to its third position. When this occurs, relay 3 66 is placed in the circuit and will be actuated to then sound the alarm. However, with the heating coil 34d in the circuit, the circuit of FIGURE 10 becomes semi-discriminating, since bimetallic element 360 is slow acting and before contact 3 62 is closed, one may replace the fuse which has been blown and correct the short circuit cause before the alarm is actuated. However, if the short circuit cannot be located and there is no fire, the arm 353i will be held in contact with terminal 336 since the thermal switch will not be activated any further thereby causing the continued heating of the bimetallic element 361i and actuation of the alarm system. If there is a fire the arm will move to terminal 34d as described above and actuate the alarm 394 before contact has been closed.

Numerous modifications are of course available on the circuit of FIGURE 10 without departing from the teachings of the invention. Particularly, a bell 3% may be utilized as shown if an auxiliary audible alarm was desired. Further, the function of the indicating lights as at and should be apparent. The indicating light 3% would immediately alight upon an initial step of the gear 328 carrying the arm 33% into contact with terminal 335. Indicating light 4% would alight upon the energization of coil 3 36 and the dropping of the bridging bars 370, 372 and 374.

By moving the contact plate 313 to its dotted line position the circuit of FIGURE 10 would be non-discriminating in that an initial energization of the coil 3% would immediately energize the coil 366 placing the bridging bars in a position to apply the necessary neutral wire to actuate the circuit alarms. Further, the circuit includes a switch as at for enabling a person to manually test the circuitry of this invention to see whether it is in order. That is, the bridging bar 4oz would obviously serve the same function as the bridging bar 36 6 to energize the circuit. A plurality of relay coils as 4%, see, etc. may further be utilized to energize the circuit in the same manner as the relay coil 3%. For example, where the terminals 312 and 314- were intended to be connected across the terminals 14d and 143 of FIGURE 1, terminals 4% and dill may be utilized across a pair of terminals as $12 and 414.

It is further apparent that auxiliary terminals such as low voltage terminals at 416 and 438 may be utilized to actuate supplementary alarm devices while high voltage terminals 420 and 422 may be used to energize high voltage alarm devices. The system. may optionally include an outlet as at 313 to provide fire protect-ion in lb the fuse panel area which is generally devoid of outlets. The operation of a fire detector carried in outlet 313 would be similar to the explanation given for the outlet 13d of FIGURE 9.

To summarize the systems comprising the teachings of this invention, a tire alarm system has been disclosed which provides for reliable fire protection while utilizing relatively simple plug-in fire detectors and conventional building electrical distribution circuitry to actuate alarm devices. The circuits may be divided into three classes. That is, the invention discloses a non-discriminating, semidiscrimin ating, and discriminating alarm systems. The first alarm system reacts equally to a fire or a conventional short circuit. The second reacts to either a conventional short or a fire but provides a time-delay for allowing an individual to change a fuse before the alarm is actuated. The third reacts exclusively to a rise in temperature such as caused by a tire. In any of the systems holding relays may be included to continue the alarm sounding until the cause of alarm is removed or the ciror" reset. It is to be particularly noted that by selective utilization of the switches and 338, the circuit of FIGURE 10 may operate as a non-discriminating, semidiscriminating or discriminating circuit.

individual design considerations are of course important in the utilization of any of these circuits in particular systems. That is, for example, while utilizing the circuit of FIGUPE 10 with the electrical distribution sy tem of FIGURE 1 shunt resistors as at 42d must be necessarily included with the relay coil These resistors must be included so that the coils as will become deenergized. The shunt resistors are necessary because as is well realized the fire detectors are in parallel with all the loads connected in that circuit and after a fuse blows are in series with the coil as at The relatively small load of the coil 3% would cause the coil to remain energized through the low resistance parallel combination of all the connected resistive loads even after the fire detector contacts open. Obviously, the circuit of FEGURE 10 requires the intermittent energization and deenergizaticn of coil 3% for satisfactory discriminating operation. Therefore, the shunt resistor 4269 must be utilized to balance the loads so that a sufficient voltage does not remain across the coil 3% to keep it energized.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resortc to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A fire detection and alarm system for use in conventional electric distribution systems comprising a temperature responsive normally open fire detector switch electrically connected between a live and neutral line, a fuse electrically connected in series with one of said lines adapted to blow upon a closure of said fire detector switch to produce assigned and alarm means energizable in response to said blowing of the fuse.

2. A fire detection and alarm system for use in conventional electric distribution systems comprising a temperature responsive normally open the detector switch electrically connected by low resistance conductor means between a live and neutral line, a fuse electrically connected in series with one of said lines adapted to blow upon a closure of said fire detector switch to produce a signal and alarm means energizable in response to said blowing of the fuse, said alarm means being normally electrically connected across a pair of like potential points, means for changing the potential of one of said points upon the closure of the fire detector switch and the blowing of the fuse.

3. A fire detection and alarm system for use in conlll ventional electric distribution systems comprising a temperature responsive normally open fire detector switch electrically connected by low resistance conductor means between a live and neutral line, a fuse electrically connected in series with one of said lines adapted to blow upon a closure of said fire detector switch and alarm means energizable in response to said blown fuse, said alarm means being normally electrically connected across a pair of like potential points, means for changing the potential of one of said points upon the closure of the fuse detector switch and the blowing of the fuse, said alarm means including an alarm device and time-delay means for deferring the actuation of said alarm device until a predetermined interval after the energization of said alarm means.

4. A fire detection and alarm system for use in conventional electric distribution including a plurality of individual circuit systems comprising a plurality of normally open fire detector switches electrically connected by low resistance conductor means between a live and neutral line, a plurality of fuses, each of said fuses electrically connected in series with one of said lines in one of said plurality of circuits and adapted to blow upon a closure of one of said fire detector switches, a plurality of relay coils normally electrically connected across a pair of like potential points, means for changing tl e potential of one of said points upon the closure of a tire detector switch and the blowing of a fuse for energizing a relay coil.

5. A fire detection and alarm system for use in conventional electric distribution including a plurality of individual circuit systems comprising a plurality of normally open fire detector switches electrically connected by low resistance conductor means between a live and neutral line, a plurality of fuses, each of said fuses electrically connected in series with one of said lines in one of said plurality of circuits and adapted to blow upon a closure of one of said fire detector switches, a plurality of relay coils normally electrically connected across a pair of like potential points, means for charging the potential of one of said points upon the closure of a fire detector switch and the blowing of a fuse for energizing a relay coil, alarm means energizable by said relay coil, said alarm means including an alarm device and time-delay means for deferring the actuation of said alarm device until a predetermined interval after the energization of said alarm means.

6. A fire detection and alarm system for use in conventional electnic distribution systems comprising at least one normally open fire detector switch, means carried by said switch for selectively closing and opening said switch in response to an increasing temperature, a step relay, said relay being selectively controlled by said switch, alarm means, said alarm means controlled by said switch and being actuated upon the completion of a predetermined number of steps of said relay.

7. The combination of claim 6 wherein said fire detector switch comprises a thermal spring, at least one container carried by said spring, a plurality of terminal pairs carried within said at least one container and a conductive fiuid carried within said at least one container for selectively bridging pairs of said plurality of pairs of terminals.

8. The combination of claim 6 wherein said fire detector switch comprises a thermal spring, a container supported by said spring, said container internally constructed with adjacent ridges forming a plurality of separated pool pockets, a pair of electric terminals fixed in said pockets, a quantity of a conductive fluid adapted to form a pool in each of said pockets so as to bridge said terminals.

9. The combination of claim 6 wherein said fire detector switch comprises a thermal spring, a plurality of containers supported by said spring, each of said plurality containers supported at a different angle relative to each other, a pair of electric terminals fixed in each of said containers, a quantit of conductive fluid carried in each container for bridging said terminals dependent on the angle of each container as varied by the thermal spring.

10. The combination of claim 6 wherein sai the detector switch comprises a thermal spring, a container supported by said spring, a pair of elongated parallel ters interr lly carried on the inner surface of said er, one of said terminals being insulated for short lengths along the length thereof and a quantity of conductive fluid carried by said container for bridging said terminals.

11. A re detection and alarm system for use in conventional electric distribution systems including a plurality of in .idual circuit systems comprising a plurality of normally open fire detector switches electrically connected between a live and neutral line, a plurality of fuses, each of said fuses electrically connected in series with one of said lines in one of said plurality of circuits and adapted to blow upon closure of one of said fire detector switches, a plurality of relay coils normally electrically connected across a pair of like potential points, means for changing the potential of one of said points upon the closure of a fire detector switch and the blowing of a fuse for energizing a rela coil, means carried by of said switches for selectively closing and opening said switch in response to an increasing emperature, a step relay, said relay being selectively controlled by said switches, alarm means controlled by said switches and being actuated upon the completion of a predetermined number of steps of said relay.

12. A temperature responsive fire detector switch comprising a thermal spring, a container supported by said spring, a pair of elongated parallel terminals internally carried on the inner surface of said container, one of said terminals being insulated for short lengths along the ength thereof and a quantity of conductive fluid carried by said container for bridging said terminals.

References @i-ted in the file of this patent UNITED STATES PATENTS 1,400,870 Croninger Dec. 20, 1,667,056 Smith Apr. 24, 1,676,922 Phelan July 10, 1,947,588 Glezun et al Feb. 20, 2,067,371 Hopkins et a1 July 9, 2,115,027 eonard Apr. 26, 2,162,098 McCabe e 13, 2,185,490 Wittmann J an. 2, 2,318,699 McCabe May 11, 2,353,498 Perry July 11, 2,479,468 Bundy Aug. 16, 2,545,760 Blanchard Mar. 20, 2,581,308 Smith Jan. 1, 2,665,345 Burton Jan. 5, 2,699,493 McCullough Ian. 11, 2,726,378 Norcross Dec. 6, 2,728,904 Schafer Dec. 27, 2,774,960 Podell Dec. 18, 2,799,848 Glantz et a1 July 16,

FOREIGN PATENTS 301,823 Great Britain Aug. 1, 

6. A FIRE DETECTION AND ALARM SYSTEM FOR USE IN CONVENTIONAL ELECTRIC DISTRIBUTION SYSTEMS COMPRISING AT LEAST ONE NORMALLY OPEN FIRE DETECTOR SWITCH, MEANS CARRIED BY SAID SWITCH FOR SELECTIVELY CLOSING AND OPENING SAID SWITCH IN RESPONSE TO AN INCREASING TEMPERATURE, A STEP RELAY, SAID RELAY BEING SELECTIVELY CONTROLLED BY SAID SWITCH, ALARM MEANS, SAID ALARM MEANS CONTROLLED BY SAID SWITCH AND BEING ACTUATED UPON THE COMPLETION OF A PREDETERMINED NUMBER OF STEPS OF SAID RELAY. 